Context: Limb lengthening has its own share of problems, obstacles, and complications, which is of great concern when used for a cosmetic indication. Aims: This study explores safe limits for cosmetic tibial lengthening and examines how age of the patient and length gained influences osteogenesis and complications. Settings and Design: This was a retrospective analytical study. Subjects and Methods: We reviewed 70 consecutive cases (140 segments) of monofocal tibial cosmetic lengthening with minimum of 1-year follow-up operated between 2006 and 2010. Statistical Analysis Used: We correlated patient's age and percentage by which bone was lengthened with external fixator index (EFI) and occurrence of obstacles and complications and did receiver operator characteristic (ROC) curve analysis to determine the safe limit. Results: Mean age of patients was 27 (16–52) years. Mean tibial lengthening was by 16.5% (4.1–27.9) of the preoperative length. Sixty segments faced 76 difficulties comprising 16 problems, 47 obstacles, and 13 complications. Patient's age positively correlated with EFI, but did not correlate with the incidence of obstacles and complications. Percentage by which bone was lengthened negatively correlated with EFI and positively correlated with incidence of obstacles and complications. ROC curve analyses (with optimum balance of sensitivity and specificity) revealed lengthening by more than 18.1% and 16.4% to be significantly associated with the occurrence of complication and more than one obstacle, respectively. Conclusions: In cosmetic tibial lengthening, increasing age increases the duration of external fixation and increased lengthening increases obstacles and complications. Great caution must be exercised in cosmetic tibial lengthening beyond 16%.

The experience and success of Ilizarov limb lengthening in achondroplasia,[1],[2] other forms of dwarfism,[2] congenital and acquired limb length discrepancy, and bone defects have extended its indication to cosmetic increase of stature.[3],[4],[5],[6] As years go by the number of patients coming forward for increase of their height is on the rise, and they have high expectations from the procedure.[4],[5],[6] The reasons for this are many – improved self-esteem, enhanced career opportunities, better participation in sports, and improved interpersonal relationships.[4],[7] Concerns and controversies have also arisen, however,[4],[5],[6],[7],[8],[9] to the extent of making the patients crippled.[7]

Experience of limb lengthening in pathological conditions has shown that over-lengthening always carries increased risk of complications and compromised function.[10],[11] In spite of reports that address the results of the Ilizarov technique[3],[4] and its variations[12],[13] in cosmetic increase of stature, there are no guidelines as to how much we can lengthen safely. Unlike limb length discrepancy and bone defects where the pathology guides the extent of lengthening, in the setting of cosmetic lengthening, the “safety factor” must be balanced with the patient's “expectations” to ensure best results.[4] Since the patients are somatically normal and fully functional, it is important that function should not be compromised in the bargain for cosmesis.

Here, we analyzed our results of lengthening of a single bone with regard to the length gained versus bone healing and occurrence of complications. Since patients who seek this procedure belong to a wide range of age, we also tried to see the impact of age with regard to bone healing and complications. We further attempted to derive guidelines for safe lengthening possible in one bone segment.

Subjects and Methods

This is a retrospective analysis of all consecutive cases of bilateral symmetrical cosmetic lower limb lengthening operated between January 2006 and December 2010. Cases of tibial monofocal lengthening alone were included in the study; those with bifocal tibial lengthening or with additional femoral lengthening were excluded to ensure comparability of cases. With the Institutional Review Board clearance, the patients with a minimum follow-up of 1 year from the date of removal of fixator were enrolled in the study. A total of 82 patients met the inclusion criteria. Twelve cases were excluded due to either lack of follow-up or incomplete medical records. Thus, there were 70 eligible subjects whose medical records, radiographs, and clinical photographs were reviewed.

All were somatically normal patients with a subjective feeling of short stature who had their tibiae elongated monofocally for cosmetic indication. The indications for surgery were (1) the presence of a clear reason to undergo limb-lengthening, (2) strong motivation, and (3) consent to undergo the procedure after complete awareness of the nature of surgery, possible complications, and the rehabilitation program. The contraindications to surgery were (1) the presence of psychologic disorders such as dysmorphophobia, (2) associated endocrine disorders such as hypothyroidism, (3) the presence of systemic illnesses related to growth and development such as renal insufficiency, and (4) the presence of dysplastic syndromes such as multiple epiphyseal dysplasia. Consent for treatment was obtained after complete psychologic assessment by a psychologist and comprehensive counseling regarding the treatment and rehabilitation. We recorded the anthropometric measurements and radiological findings for length, any limb length discrepancy, deformity, or focal bone pathology.

Operative Technique we used the standard three ring construct for leg segment lengthening adhering to the classical Ilizarov technique using only fine wires and no half pins. The frame was assembled in a progressive fashion. The proximal most ring was 5/8 ring (or alternatively an incomplete one made of stacking two half rings one over the other) with gap posteriorly to permit maximum knee flexion. It was fixed to tibial metaphysis with four tensioned wires, two of which were olives from both directions, and one of them through the head of fibula. Most of the soft-tissue resistance is experienced in lateral and posterior aspects in tibial lengthening, and hence, the angle between this ring and the proximal tibial axis was open medially and anteriorly to prevent valgus-procurvatum deformity. The second ring is placed 11–17 cm distal to the first ring (depending on the preoperative length of the tibia) perpendicular to the axis of the tibia. This distance was maintained to prevent undue stretching of skin and soft tissue during the distraction process. This ring is fixed to tibial diaphysis with three wires, two of them are opposing olive wires (or alternatively 1–2 wires with additional two bicortical cantilever wires attached to above and below the ring obliquely with posts). Soft tissue bulk is provided at the area between these two rings by displacing the skin proximally as these wires are being inserted. The first and the second rings are connected to each other with four threaded rods through manually constructed biaxial hinges attached to the proximal ring. The distal ring is kept at the supramalleolar level parallel to the ankle joint and fixed with three wires, one of which is an olive wire passing through fibula and tibia stabilizing the distal syndesmosis. This ring is connected to the middle ring with four threaded rods.

Once this assembly was completed, we did the fibular corticotomy at the junction of middle and distal thirds. Tibial corticotomy was done by classical Ilizarov technique just below the tibial tuberosity. After loosening all four threaded rods from the hinges, a small incision (0.5 cm) was made on the anterior surface of tibia. A chisel of appropriate size is inserted up to the bone and rotated to the right direction, corticotomy of the anterior, medial, and lateral cortices were made. Rotational osteoclasis completed the corticotomy of the posterior surface. The rings were brought back to the original positons, and the threaded rods were reconnected. The wound was closed with a single suture.

PostOperative care distraction commenced on 7th postoperative day at 1 mm/day over four fractions and adjusted as per clinico - radiological monitoring. We encouraged full range of motion and full weight-bearing crutch-assisted walking as much as possible from 2nd postoperative day. Radiographs were taken every 2 weeks to assess the quality of regenerate and monitor for any incident deformity. After gaining the planned length, fixators were left in place for necessary time to allow consolidation of the regenerate with monthly radiological monitoring. Almost all patients needed minor readjustments during and after distraction to maintain the mechanical axes in all three planes. The decision to remove the fixator was taken based on satisfactory stress test after the removal of the connecting rods and evidence of radiological consolidation as evidenced by cortical continuity of at least three cortices across two orthogonal views.

After removal of the fixator, patients were given cast extending from thigh to supramalleolar region for 2–4 weeks depending on the findings of stress test before fixator removal. The patients were followed up every 3 months for 1 year and yearly thereafter.

We calculated the lengthening index (LI), maturation index (MI), and external fixator index (EFI)[14] as the measure of ability to lengthen and healing potential of the regenerate. LI is the number of days spent in distraction for every centimeter of bone lengthening. MI is time to consolidation per centimeter of distraction gap. EFI is the number of days spent in external fixator for every centimeter gained. We also systematically recorded all difficulties encountered during treatment and how they were managed. Difficulties were classified as according to Paley[15] into problems, obstacles, and complications. Problems could be completely resolved without any operative intervention; difficulties needed an operative intervention. All intraoperative injuries and difficulties that were not resolved at the end of treatment were considered true complications.

We believe that the percentage of bone lengthening affects bone regeneration and difficulties more than numerical value of length gained.[11] For each patient, we calculated the percentage by which the tibia was lengthened and tried to relate it to EFI and occurrence of obstacles and complications. The length of the tibia was measured preoperatively and after removal of fixator as the distance between the center of tibial spine to distal articular surface of tibia in line with the center of the talar dome in the standard anteroposterior radiograph. We also analyzed if patient's age influences bone regeneration and incidence of obstacles and complications.

Quantitative data were expressed as mean (range) or numbers (proportion [%]). Spearman's correlation coefficient (chosen in case variable had nonparametric distribution or outliers, reported with 95% confidence interval [CI]) was determined to assess the strength of association between variables. We considered occurrence of all “problems” and up to one “obstacle” during the whole treatment duration as part and parcel of Ilizarov technique. Considering occurrence of more than one obstacle and even one complication as unacceptable, receiver operator characteristic (ROC) curve analysis[16] was done to determine a safe cutoff for cosmetic limb lengthening with optimum balance of sensitivity and specificity (determined by maximum value of Youden's index). Area under the ROC curve (a measure of discriminative ability [ability to differentiate between those with and without the outcome in question]) was reported with standard error (SE) and 95% CI. Two-tailed alpha <0.05 was set beforehand as significant and MedCalc v 15.8 (MedCalc Software, Ostend, Belgium) was used for statistical calculations.

Results

We had 70 patients and 140 tibial segments. The average age of the group was 27 years (16–52) with 44 males and 26 females. The mean preoperative height was 163.5 cm (143–181), and the mean height gained was 5.9 cm (1.5–10). In three patients, the distraction was stopped at 1.5 cm, 1.5 cm, and 2 cm, respectively, as per patient preference. The mean percentage by which tibia was lengthened was 16.5% (4.1–27.9). The demographic, clinical, and intervention characteristics are detailed in [Table 1]. The mean LI, MI, and EFI were 14.5 (6–31), 23 (6–72), and 39 (19–100) days per centimeter, respectively. The minimum follow-up available was 2 years, and the mean follow-up was 4.3 (2–8) years.

A total of 76 difficulties occurred in 60 out of 140 segments (43%) and 15 segments (10.7%) faced more than one difficulty. Overall, there were 16 problems (21%), 47 obstacles (62%), and 13 complications (17%) [Table 2].

The problems were pin tract infection, common peroneal neuropathy, and delayed regeneration. Pin tract infection in all cases settled with regular dressings and oral antibiotics. None of them progressed to deep infection or osteomyelitis. Neuropathy was managed by reducing the dose of distraction, physiotherapy and splinting, and pharmacological supplementation (intramuscular injection of neurotropic medications such as proserin or Galantamine and Vitamins B1, B6, and B12 for 10–14 days). The functions of the nerve recovered completely in all cases. Delayed regeneration settled with expectant management by increasing the duration of fixator.

Equinus was the most common obstacle to tackle and was managed by extension of the apparatus below ankle, use of percutaneous achilles tenotomy, and correction by gradual distraction. Breakage of wires needed exchange under anesthesia. Other obstacles were early fibular consolidation that needed repeat osteotomy, deformity of regenerate that needed realignment under short anesthesia (in one segment due to associated translational and rotational components), and delayed regeneration that needed intervention. In delayed regeneration that did not settle with expectant management for 3 months [Figure 1]a, wires were applied through the regenerate [Figure 1]b. This was intended to stimulate bone regeneration avoiding the need for bone graft.[4]

True complications were as follows. Late deformation of regenerate [Figure 2]a was corrected in five out of seven segments by reapplication of Ilizarov fixator [Figure 2]b; two patients refused further surgery and accepted the axial deformity between 5° and 10°. Late fracture through the regenerate in two patients was managed with successfully by Ilizarov osteosynthesis. One patient had mild knee subluxation and was managed by physiotherapy and mobilization exercises since he refused another surgery. Despite extensive physiotherapy one patient had restricted range of dorsiflexion of the ankle. Another patient developed subtalar valgus deformity and was given an ankle foot orthosis. The patient who had incomplete consolidation of regenerate also preferred customized orthotic management.

Figure 2: (a) Anteroposterior and lateral radiographs of leg showing deformation of regenerate while on cast after removal of fixator, (b) Reapplication of Ilizarov apparatus with flexible intramedullary rods for deformity correction

On statistical analysis, we found that age had a positive correlation with EFI (Spearman coefficient 0.29, 95% CI for rho 0.13–0.43, P = 0.0006), but age was not associated with increased incidence of obstacles or complications (Spearman coefficient 0.02, 95% CI for rho 0.15–0.18, P = 0.84). The percentage by which the bone was lengthened had a negative correlation with EFI (Spearman coefficient −0.5, 95% CI for rho − 0.61–−0.36, P < 0.0001) signifying more lengthening did not mean poorer regeneration. However, it had a positive correlation with the incidence of obstacles and complications (Spearman coefficient 0.31, 95% CI for rho 0.15–0.50, P = 0.0002).

On ROC curve analyses lengthening by more than 16.4% could discriminate the occurrence of more than one obstacle with a sensitivity of 72% and specificity of 60.2% (area under ROC curve 0.68 [SE-0.05], 95% CI 0.59–0.75, P = 0.0009) [Figure 3]. Lengthening by more than 18.1% could discriminate the occurrence of a complication with a sensitivity of 83.1% and specificity of 64.6% (area under ROC curve 0.76 [SE-0.05], 95% CI 0.68–0.82, P < 0.0001) [Figure 4].

Figure 3: Receiver operating characteristic curve analysis of likelihood of getting more than one obstacle with percentage by which the bone was lengthened (Youden's index point highlighted)

Reports on the use of distraction osteogenesis for cosmetic limb lengthening are limited,[3],[4],[5],[6] and none of them has analyzed the aspect of risks versus benefits, nor established safe guidelines for extent of limb lengthening or appropriate age.[8],[9]

Our results regarding age and EFI mirrors the published results by Fischgrund et al.[17] and Sakurakichi et al.[14] in their studies on limb lengthening in pathological states. Older age is associated with slower healing; in our patients of 16–52 years age group, there was no increased incidence of obstacles and complications with age, however, it had a positive correlation with EFI. Thus, the major concern for cosmetic lengthening as age advances is the time spent with external fixator.

Another factor to examine is whether increasing percentage of limb lengthening causes disproportionate increase in the time spent in external fixator. Our results, on the contrary, show a negative correlation which is also seen in studies by Noonan et al.,[18],[19] Yun et al.,[11] Fischgrund et al.,[17] and Sakurakichi et al.,[14] with either absolute lengthening or percentage by which the bone was lengthened.

However, correlation coefficient (rho) was 0.29 between age and EFI, and 0.31 between percentage of bone lengthened and incidence of obstacles and complications. Although these relationships were statistically significant, such low correlation coefficients imply low clinical relationships and hence should not be over-emphasized or exaggerated.

The prohibitive factor of limb lengthening has always been complications; however, lack of standardized definition of complications across various studies warrants a cautious view of their actual occurrence. Our study used an objective, reproducible index to measure them and results show that limb lengthening >16.4% and 18.1% could discriminate higher probability of occurrence of more than one obstacle and complication, respectively, with sufficient sensitivity and specificity so as to form a useful clinical guide to counsel patients about prognosis. Similar data are available for limb lengthening in pathological states. Dahl et al.[20] report higher incidence of major complications when lengthening exceeded 15%. Yun et al.[11] document occurrence of at least two significant difficulties per procedure when lengthening exceeded 20% but did not consider it to be prohibitive to achieve the desired length. These observations may be valid for pathological states such as congenital deficiencies, dysplasias, posttraumatic and postinfectious sequelae but should not be extrapolated to a cosmetic setting. In his paper on limb lengthening in congenital limb deficiencies, Karger et al.[21] report increased complications and poorer results when lengthening exceeded 25%. Here again, children represent a different subset of patients that may not be comparable to the young- and middle-aged cosmetic patient cohort.

Area under the ROC curve measures the accuracy of the variable under study to discriminate outcomes into those with and without the disease in question (occurrence of more than one obstacle or complication in our study). A minimum value of 0.7 is desirable as a measure of fair performance.[22] Percentage by which the bone was lengthened satisfied this criterion in our study implying fair accuracy in clinical use. A higher cutoff of percentage by which bone was lengthened would increase sensitivity and lower specificity while a lower cutoff would do the opposite.

We reemphasize that this study was done on a group of carefully selected patients, treated by highly experienced surgeons and therapists, in an inpatient setting dedicated to the Ilizarov technique. We faced many problems, obstacles and complications but were able to handle most of them with well-chosen interventions. Six out of 140 segments were left with less than optimal final outcome (axial deviation <10°-2, minor knee subluxation-1, reduced dorsiflexion of ankle-1, stiff ankle and foot deformity-1, incomplete consolidation of regenerate-1). All except impaired dorsiflexion could have been improved by further interventions but these patients were not willing for further surgery.

The occurrence of problems, obstacles, and complications across available studies in cosmetic limb lengthening with variations in the surgical technique is summarized in [Table 3]. We also acknowledge our interventions to manage these complications and the variations that exist in literature regarding their management.

Table 3: Occurrence of problems, obstacles, and complication in cosmetic bilateral lower limb lengthening across studies available in literature

At the earliest evidence of common peroneal neuropathy manifested by appearance of paresthesia, numbness or weakness of ankle, and toe dorsiflexors, we reduce the dose of distraction and start pharmacological supplementation. Our current regimen consists of intramuscular injection of proserin 0.05% 1 ml/day for 10 days and Vitamin B1 and B6 (5%, 1 ml/day) on alternate days for 10 days. For equinus deformity while on fixator, we resort to percutaneous achilles tenotomy (three incision technique) and do gradual distraction by extending the fixator to the calcaneum. This, in our view, lengthens the tendon by neohistiogenesis without weakening the gastrosoleus complex. In contrast, Catagni et al.[3] and Guerresch and Tsibidakis[5] have reported the management of equinus by acute tendo-achilles lengthening in a good percentage of their cases who underwent cosmetic tibial lengthening. Elbatrawy and Ragab[6] performed modified Strayer technique for tendo-achilles tightness in their patients of cosmetic limb lengthening. Rozbruch et al.[23] report gastrocsoleus recession (GSR) during various stages of treatment as their technique of correcting equinus while performing tibial lengthening for various reasons. They report that lengthening beyond 4.2 cm or 13% of the original length carries significant chances for GSR.

Our center has developed three stimulation techniques to accelerate the consolidation of regenerate in cases with delayed regeneration, which are adopted based on surgeon's preference. The first is to drill through the regenerate and adjacent parent bone. The second is to place oblique or transverse K-wires into the regenerate till it starts showing improvement. A third variation is to keep crossed oblique olive wires from proximal-distal across the regenerate, with their distal aspect connected to distal ring through threaded rods. They are then distracted 1 mm/day and to gently distract the regenerate distally till it shows evidence of consolidation.[4] The second technique was employed in all the three cases of this series that showed delayed regeneration.

The study has numerous limitations. First, the study was retrospective from hospital records. Patients were not assessed directly as part of the study. Twelve eligible patients who had to be excluded from the study due to lack of follow-up or complete medical records could have potentially biased the results. Since surgeons themselves recorded the follow-up, assessment bias is likely. The patients went through a rigorous selection process involving psychological assessment and counseling - which we think is necessary - this could have contributed to selection bias. We did not have data if numerical gain in height translated to fulfilment of patient objectives. Objective scores for functional outcome and patient satisfaction could have enriched the study, but we could not incorporate them due to nonavailability of data. In spite of following a strict protocol for surgical technique, rehabilitation and follow up, there could have been variations among patients with regard to time and degree of weight bearing, distraction rate as guided by patient tolerance also and subjective elements on radiological assessment determining the duration of external fixator – all these could have acted as confounders.

Nowadays, cosmetic lengthening is done increasingly with hybrid techniques such as lengthening over nail[13] lengthening and then nailing[12],[24] or using an internal lengthening devices. Although the information obtained from this study may be applied to other limb lengthening devices, there is a significant gap between these. This decreases its clinical relevance of the current study which has studied cases of tibial lengthening done by classical Ilizarov technique only.

Conclusions

Cosmetic limb lengthening using Ilizarov technique should be done only in carefully selected, well-motivated patients after repeated sessions of preoperative counseling. Problems, obstacles, and complications must be expected during treatment; however, most of them can be managed by carefully selected interventions without permanent sequelae or disability. With higher age, there is chance of increased duration of external fixation; with increased lengthening, there is increased incidence of obstacles and complications. Great caution must be exercised if lengthening of the tibial segment is contemplated by more than 16% of its original length.